A 26-year-old man fatally stabbed his 25-year-old roommate before stabbing himself during a scuffle in their Queens home Wednesday evening, police sources said.

The woman — who was stabbed in the back and neck inside the building on Stanhope Street near Onderdonk Avenue in Ridgewood around 11:25 p.m. — was rushed to Wyckoff Heights Medical Center, where she was later pronounced dead.

Her roommate then stabbed himself in the leg, and was taken to Elmhurst Hospital Center in stable condition, cops said. He is in custody but has yet to be charged, according to police.

Cops did not immediately know what the argument was about.